Nope, a whole playable game! Which could be structured essentially as an adventure, but the idea is that you don't need any external reference to play it. For an excellent example of a short, complete game, check out Lady Blackbird.

Queue: You should provide all the rules and other info necessary to play the game. If you want to structure it around a single "adventure," that's fine and there are plenty of precedents for that (The Mountain Witch comes to mind, for example, from Game Chef 2004). If you want to get a sense of how previous chefs have approached it, I'd suggest reading a couple of the drafts produced in previous years. The games from last year are reviewed here and some of the links to those drafts should still be live.

Totally! Also remember that this 3,000 words isn't everything you're going to include in the game ever. It's just the playable draft that you're turning in for Game Chef. Anything you do with it after that -- including adding more material, etc. -- is entirely up to you.

It's really up to you. Google docs are okay, also blog posts, pdfs, etc. Really, though, I find that people most often read things that are just posted in a forum thread or on a blog. There's something about the extra effort -- however minimal -- required in downloading or opening a separate file that seems to be a barrier sometimes.

Paolo: Your Game Chef game is going to be randomly reviewed by several other people who may not have any experience with the Solar System or whatever other game system you might want to base your game on. So your submission has to include all the information someone might need to play the game. Plus, it's really supposed to be a game design competition, not a scenario-writing competition, so if you're just going to use the Solar System more or less as-is, this probably isn't the best contest for that idea. On the other hand, if you're going to adapt the Solar System significantly and can include all the information needed to play in 3,000 words, then, by all means, go for it. Does that make sense?

1)Do pre-made character sheets count as supplimental material, if they are integral parts of the game, or do they count towards the 3000 words?

2)Do I need to share my stuff here as I'm working on it? I'm trying to not read through other people's threads so I don't accidentally absorb an idea... and I'm brand shiny new to this whole Game Chef thing, so I'm kinda shy o.O

Eleri, with regard to your #2, the answer is: only if you find it helpful to your design process. There are no rules about sharing what you're doing in a thread or reading about what people are doing. Participate in that way as much or as little as you see fit. The only rule about showing anything about your design is that you have to submit it by the 15th!